Superhydraulic forging method and apparatus



May 21, 1968 R. C. GEITZ SUPERHYDRAULIC FORGING METHOD AND APPARATUS Filed Oct. 20, 1965 INVENTOR ROBERT C. GEITZ ATTORNEY United States Patent 3,383,891 SUPERHYDRAULIC FORGING METHOD AND APPARATUS Robert C. Geitz, 7 Hoplea Road, Simsbury, Conn. 06070 Filed Get. 20, 1965, er. No. 498,224 9 Claims. (Cl. 72-57) This invention relates generally to an improved forging method and apparatus and particularly to a method and apparatus for closed die cold forging.

When metal is subjected to sufficiently high pressures there is a change in the physical properties of the metal among which is a tremendous increase in the ductility of the metal. These changes are brought about solely through the application of pressure with the high pressures that are here being referred to being of a value such that the metal flows, or, to express this in another way, inelastic action takes place. As a result of this tremendous increase in ductility, even giving a substantial degree of ductility to metals that are normally considered non-ductile, forging of the metal may be accomplished much more readily and satisfactory forgings obtained which were previously possible only with great difficulty.

In accordance with the present invention, there is provided a method and apparatus for closed die forging wherein the metallic billet or work piece is placed in a bath of hydraulic fluid, the pressure of which is raised to a sufficiently high value, such as several kilobars depending upon the metal of the billet or work piece, so that inelastic action takes place in the metal of the billet with the ductility of the metal being very substantially increased relative to that prevailing at atmospheric pressure. While under the influence of this high pressure the billet or work piece is subjected to the action of a pair of closed impression dies, with the work piece being shaped in accordance with and filling the die cavity as the dies are forceably brought into forging relation with each other. After the work piece is thus shaped the dies are opened for removal of the forging and either simultaneously with or prior to the opening of the dies, the high fluid pressure is released or reduced to a value below that at which the inelastic action of the metal of the work piece takes place.

This improved forging method of the invention and the apparatus for carrying it out provide numerous advantages. It extends the benefits of cold forging to complex asymmetrical parts while heretofore cold forging 'has been limited to symmetrical parts formed by upsetting, aswaging, cold heading, and forward or backward extrusion. Furthermore, it will permit brittle and nonductile metals to be worked at ordinary temperatures which was heretofore not possible or not practicable. Still further, as contrasted with hot forging there is no scale and no de-carburization with the improved process and close dimension tolerances may be maintained and a superior finish produced. Moreover, superior tensile strength is produced due to the cold working of the metal. With the improved process of the invention the special lubrication required by present cold forging operations is not needed because the hydraulic fluid acts as a lubricant.

Thus, the advantages of cold forging are obtained with the invention and the disadvantages of hot forging are eliminated with it being possible to forge materials and parts with this improved process which could heretofore 0 "ice only be forged by hot forging and in some instances not at all. The process of the invention is a cold forging process and by this it is meant that the work piece is not heated to the high temperature employed in what is customarily known as hot forging, i.e., 1700 F. or higher for steel forgings. With the process of the invention the work piece is not to be at such a temperature that its physical properties are changed, thus for steels the work piece is to be at 1000 or under, with it being preferred to carry out the process of the invention with the work piece being at room temperature.

It is accordingly an object of the invention to provide an improved cold forging method and apparatus.

It is a further object of the invention to provide such an improved method and apparatus wherein the billet or work piece is first subjected to a high fluid pressure such that inelastic action takes place within the metal of the work piece with the work piece being subjected to the action of a pair of closed impression dies while under the influence of this high pressure.

Other and further objects of the invention will become apparent to those skilled in the art as the description proceeds.

With the aforementioned objects in view, the invention comprises an arrangement, construction and combination of the elements of the inventive organization in such a manner as to attain the results desired as hereinafter more particularly set forth in the following detailed description of an illustrative embodiment, said embodiment being shown by the accompanying drawing wherein the single figure is a diagrammatic representation of the forging apparatus of the invention and by means of which the im proved process may be carried out.

Referring to this drawing, there is disclosed therein a' heavy walled housing 10 within which is formed chamber 12 extending upwardly from this chamber through the upper end of the housing is the cylindrical passage 14. Slideably received in this passage is the piston 16 which has associated with it seal 18 to prevent fluid leakage from chamber 12 through the narrow passage between the piston and passage 14.

Vertical reciprocation of piston 16 is provided through a suitable actuating device designated generally 20 and including a cross member 22 and relatively large vertically extending rods 24 which in turn may form part of a press or hydraulic mechanism.

There is provided within the chamber 12 a pair of closed impression dies. One of these dies is formed on the end of the piston 16 with the cavity being identified as 26 while the other die 28 is mounted on the floor of the chamber and has a die cavity identified as 30.

The chamber 12 is filled with a suitable hydraulic liquid 32 and there is positioned within the chamber 12 intermediate the dies a billet or work piece 34.

Fluid pressure is relieved from the chamber 12 through the passage 36 which communicates with the conduit 38. Within this conduit there is provided a relief valve 40 which is set so that fluid pressure is bled from the chamber 12 when the pressure reaches a predetermined high desired value.

The metal of billet 34 and the material of which the housing 10, piston 16, and die 28 are dabricated is such HEM. the fluid pressure necessary to cause inelastic action to take place in the metal of the billet is substantially 3 lower than the corresponding fluid pressure for the material of the housing 10, die 28 and piston 16.

Hydraulic fluid is admitted to the chamber 12 through the passage 38 which connects with the conduit 41. This conduit in turn communicates with a supply of the hydraulic liquid and provided within this conduit is the check valve 42 which prevents reverse flow through conduit 41 and passage 38.

In operation the actuating device 20' moves the piston 15 downward such that the pressure in chamber 12 in creases to a predetermined high value whereat the valve 4!) permits the fluid to be bled from the chamber. The high value of the pressure within the chamber 12 is such that it is at least equal to and preferably above the pressure at which inelastic action takes place in the metal of the work piece 34 but below that at which inelastic action takes place within the material of the housing and the dies. With the pressure in chamber 12 thus elevated the piston 16 is brought forceably downward such that the dies are in forging relation and the work piece 34 shaped in accordance with the configuration of the die cavity. Because of the increased ductility of the metal of the work piece subjected to the high pressure in chamber 12, this forging action is readily and satisfactorily accomplished. After the work piece is thus shaped the piston 16 is elevated and immediately upon its elevation and through the action of such elevation the pressure within the chamber 12 is relieved with hydraulic liquid being then drawn through the passage to the conduit 40 and passage 38 to the chamber 12 as the piston is progressively moved upward. If desired, a timing device may be employed to relieve the pressure in chamber 12 prior to the release of the dies by the upward movement of piston 16.

The diagrammatic arrangement illustrated in the drawing, for the sake of simplicity, contains no representation of a gate system or material handling system for admitting the Work piece into and delivering the forging from the chamber 12 and intermediate the dies. In the illustrative arrangement the work piece may be delivered into and the finished forging retrieved from chamber 12 by lifting piston '16 from passage 14 and then manually performing these operations.

While I have illustrated and described a preferred embodiment of my invention it is to be understood that such is merely illustrative and not restrictive and that variations and modifications may be made therein without departing from the spirit and scope of the invention. I therefore do not wish to be limited to the precise details set forth but desire to avail myself of such changes as fall within the purview of my invention.

I claim:

1. A closed die cold forging operation wherein a metallic shape is formed by squeezing a metal billet between dies which define a die cavity, comprising the steps of surrounding the billet with a fluid, increasing the pressure of the fluid surrounding the billet to a high value where the ductibility of the metal of the billet is substantially increased, while thus subjected to this high pressure subjecting the billet to the action of the dies to cause metal of the billet to occupy and conform to the die cavity, thereafter reducing said pressure to a value where it has substantially no effect on the ductibility of the formed metal and not before such pressure reduction releasing the die portions to permit removal of the forging.

2. A cold forging process for forming a metal billet between dies comprising surrounding a metal work piece with a fluid pressurized to a value such that the metal of the work piece flows, while the pressurized fluid is thus applied to the work piece shaping said work piece between said dies and retaining the formed billet in the desired shape, and while thus shaped releasing said pressure.

3. A cold forging process for forming a work piece to the configuration of a cavity comprising surrounding a metal work piece with a hydraulic fluid pressurized to a value such that the metal of the work piece flows, while this pressurized fluid is thus applied to the work piece shaping said work piece to the configuration of the cavity and retaining it in the desired shape, and while thus shaped releasing said pressure.

4. A closed die cold forging operation for forming a metal billet between dies that define a cavity comprising bathing the metal billet in a liquid, raising the pressure of the liquid to a value where inelastic action of the metal of the billet occurs, while subjecting the billet to such pressure performing the forging operation via the dies, and thereafter lowering the pressure of the liquid to a value below that where inelastic action of the metal occurs at least as soon as the die release occurs.

5. In a forging operation wherein a pair of closed impression dies defining a cavity therebetween are brought in forging relation to act upon :a metallic work piece to produce a forging the improvement comprising immersing the work piece in a body of liquid, raising the pressure of said liquid to a value at least equal to that at which inelastic action takes place in the metal of the work piece, While subjected to this high pressure bringing said pair of dies together to :act upon the work piece, thereafter simultaneously releasing said dies and removin g said high fluid pressure.

6. A forging device for cold forging comprising in combination:

(a) means forming a chamber containing a non-compressible fluid;

(b) a pair of forging dies in said chamber forming a die cavity and adapted to be brought together on a metallic work piece in a forging operation;

(c) means operative to raise and maintain the pressure in the chamber to a value at or above that at which inelastic action occurs in the metal of said work piece;

(d) means operative while the pressure is thus raised to bring said dies together in forging relationship on a work piece; and

(e) means for opening the forging dies and releasing said pressure.

7. A forging apparatus comprising in combination means providing a chamber capable of withstanding extremely high internal pressure with said chamber containing a liquid, a pair of closed impression dies immersed within said liquid and forming a die cavity, means for manipulating said dies to move them into and out of forging relation, means capable of raising the pressure of the liquid within said container prior to the movement of the dies into forging relationship to forge a metallic work piece with the pressure being raised to a value at least sufliciently high so that inelastic action takes within the metal of the work piece, means to regulate said elevated pressure including a pressure responsive system for bleeding liquid from the chamber, and means for lowering the pressure within the chamber to a value below that at which inelastic action takes place within the metal of the work piece at least as soon as said dies are moved out of forging relation.

8. A forging device comprising in combination means forming a chamber filled with a liquid, and adapted to have immersed therein a metallic work piece to be shaped by forging, means for pressurizing said liquid to a value at least equal to that at which inelastic action takes place wthin the metal of the work piece, means for shaping said work piece by forging while immersed within and surrounded by this high pressure liquid, this last-named means including a pair of closed impression dies forming a die cavity and between which said work piece is embraced during forging, and means for depressurizing said liquid at least as soon as said work piece is released from the action of said shaping means.

9. A forging apparatus comprising in combination means forming a heavy walled chamber containing a liquid and having a passageway extending therefrom, piston means reciprocally mounted in said passageway, means for forcibly moving said piston axially of the passageway, a pair of closed impression dies dis-posed within the chamber, forming a die cavity, and operated by said piston means being moved into and out of forging relation thereby for forging a work piece, a pressure responsive bleed system for bleeding liquid from the container when the pressure thereof is at least equal to the pressure at which inelastic action takes place in the metal of the work piece, and means for admitting liquid to the chamber as the piston is moved out of said passageway.

References Cited UNITED STATES PATENTS 2,558,035 6/1951 Bridgman 72-60 2,648,125 8/1953 McKenna et al. 72-56 2,649,067 8/1953 Kranenberg 726l FOREIGN PATENTS 1,120,409 12/ 1961 Germany.

RICARD J. HERBST, Primary Examiner. 

1. A CLOSED DIE COLD FORGING OPERATION WHEREIN A METALLIC SHAPE IS FORMED BY SQUEEZING A METAL BILLET BETWEEN DIES WHICH DEFINE A DIE CAVITY, COMPRISING THE STEPS OF SURROUNDING THE BILLET WITH A FLUID, INCREASING THE PRESSURE OF THE FLUID SURROUNDING THE BILLET TO A HIGH VALUE WHERE THE DUCTIBILITY OF THE METAL OF THE BILLET IS SUBSTANTIALLY INCREASED, WHILE THUS SUBJECTED TO THIS HIGH PRESSURE SUBJECTING THE BILLET TO THE ACTION OF THE DIES TO CAUSE METAL OF THE BILLET TO OCCUPY AND CONFORM TO THE DIE CAVITY, THEREAFTER REDUCING SAID PRESSURE TO A VALUE WHERE IT HAS SUBSTANTIALLY NO EFFECT ON THE DUCTIBILITY OF THE FORMED METAL AND NOT BEFORE SUCH PRESSURE REDUCTION RELEASING THE DIE PORTIONS TO PERMIT REMOVAL OF THE FORGING. 